The aspects disclosed herein relate to the field of molds for curing or vulcanizing vehicle tires, and more particularly molds of the sectored type.
This type of mold mainly includes two shells that each mold one of the lateral sidewalls of the tire, a plurality of sectors that mold the tread of said tire and are radially movable between an open position and a closed position of the mold, and at least one clamping ring for allowing the sectors to move radially.
The shells and the sectors define an inner space that is intended to be brought into contact with the unvulcanized green form of tire. For more details concerning such a type of sectored mold, reference may be made for example to the documents DE 1 808 811, U.S. Pat. No. 3,797,979, EP-A2-0 701 894 and EP-B1-2 040 911.
The manufacturing of the tire, and more particularly the vulcanization phase, requires that a pressure is applied to the green tire in order to press it against the internal faces of the mold and that heat is supplied to the mold. It is also known practice to heat the mold by electrical induction and/or by magnetic induction. It is also known practice to heat the mold by means of a heat-transfer fluid such as pressurized water vapour.
In order to optimize the curing of the tire, one solution consists in heating the two shells of the mold to and keeping them at a temperature different from that to which the sectors are heated.
However, in the closed position of the mold, each shell is generally provided to bear directly against the sectors in the radial direction. Such instances of contact promote heat transfer by conduction inside the mold, between the sectors and the shells. This can be incompatible with optimal curing of the tire.
Also known, from the Patent EP-B1-0 522 374, is a sectored mold that also comprises two lateral rings that are fastened to the sectors and bear radially against the shells in the closed position. Such rings aim to avoid the occurrence of molding burrs on the manufactured tires and are made of steel, like the sectors and the shells, such that only steel parts come into contact when the mold is closed.
This solution also promotes heat transfer by conduction between the sectors and the shells and also a uniform distribution of the temperature in the mold.